1. Field of the Invention
The present invention relates to a flexible electrochromic device and a method of manufacturing the same, and more particularly, to a flexible electrochromic device, which includes a patterned insulating layer, a nanocrystalline semiconductor layer adsorbed on a predetermined pattern and an electrochromic material layer improving contrast and operational properties of a display device, and to a method of manufacturing such an electrochromic device.
2. Description of the Related Art
An electrochromic device is a device that can exhibit a visual chromism effect through chemical or physical transformation of the molecular structure of electrochromic material caused by various external stimuli including electrical stimulus. Such a device is based on the principle of inducing visual change in color or shade due to a redox reaction. The redox reaction is caused by the transfer of ions or electrons contained in the electrolyte supplied between a transparent electrode and a counter electrode into an electrochromic material layer upon the generation of potential difference between the two electrodes by external electrical stimulus. The electrochromic device can control the optical properties and thus can be used for information treatment, such as the recording, display and output of information data.
In regard to the electrochromic device, WO97/035227 discloses a nano electrochromic display, in which electrical active material such as viologen is adsorbed on a nanocrystalline semiconductor material. In addition, WO98/035267 and U.S. Pat. No. 6,870,657 disclose an electrochromic device including semiconductive metal oxide having an adsorbed redox chromophore. However, since the nanocrystalline semiconductor material should be formed at high temperatures of 450° C. or more in order to exhibit desired properties, it is difficult to apply on a flexible transparent substrate.
The flexible nanocrystalline electrochromic device, which is a display device using a flexible transparent substrate such as plastic, is receiving attention in terms of having wide application fields by virtue of the flexible properties thereof. However, in the case where the flexible substrate is used, a process of forming metal oxide such as TiO2, which is the main constituent of the semiconductor electrode, should be conducted at low temperatures of 200° C. or less, and thus, high reliability of TiO2 cannot be assured, undesirably exhibiting insufficient display performance.
In addition, Japanese Patent Laid-open Publication No. 2002-100416 discloses a photoelectric conversion device manufactured by attaching a semiconductor particle layer to the surface of the conductive layer of a conductive support via electrophoretic deposition.
However, such techniques suffer because they do not include a process of forming a nanocrystalline pattern on a flexible substrate, and achieving low contrast and long response time.